Write line design in MRAM

Abstract

A magnetic random access memory device (MRAM) and the method for forming the same are disclosed. The MRAM has a magnetic tunnel junction (MTJ) device, a first write line, and a second write line orthogonal to the first write line, wherein at least one of the first and second write lines has a width narrower than that of the MTJ.

1. A magnetic random access memory device comprising:
 a magnetic tunnel junction (MTJ) device having a width; 
 a first write line having a first write line width; and 
 a second write line orthogonal to the first write line, the second write line having a second write line width, 
 wherein the first and second write line widths are smaller than the width of the MTJ, and at least one of the first and second write lines widths is about half the width of the MTJ. 
 
   
   
     2. The magnetic random access memory device of  claim 1  wherein both the first and second write widths are about half the width of the MTJ. 
   
   
     3. The magnetic random access memory device of  claim 1  wherein at least one of the first and second write lines has a width larger than half of the width of the MTJ. 
   
   
     4. The magnetic random access memory device of  claim 3  wherein the width of the write line that is larger than half of the width of the MTJ is smaller than the width of the MTJ. 
   
   
     5. The magnetic random access memory device of  claim 1  wherein at least one of the first and second write lines is integrated with a shielding layer adjacent to the at least one of the first and second write lines. 
   
   
     6. The magnetic random access memory device of  claim 5  wherein the shielding layer further includes Mn. 
   
   
     7. The magnetic random access memory device of  claim 1  wherein at least one of the first and second write lines is connected to the MTJ through a buffer layer with a flat contact surface. 
   
   
     8. The magnetic random access memory device of  claim 7  wherein the contact surface between the buffer layer and the MTJ is formed by using a chemical-mechanical polish process. 
   
   
     9. A magnetic random access memory device comprising:
 a magnetic tunnel junction (MTJ) device; 
 a first write line; and 
 a second write line orthogonal to the first write line, 
 wherein both the first and second write lines are narrower in width than the MTJ. 
 
   
   
     10. The magnetic random access memory device of  claim 9  wherein at least one of the first and second write lines is integrated with a shielding layer adjacent to the at least one of the first and second write lines for enlarging a magnetic flux efficiency when conducting a current therein. 
   
   
     11. The magnetic random access memory device of  claim 10  wherein the shielding layer contains Mn. 
   
   
     12. The magnetic random access memory device of  claim 9  wherein the width of at least one of the first and second write lines is larger than about half the width of the MTJ. 
   
   
     13. The magnetic random access memory device of  claim 12  wherein the width of the write line larger than half of the width of the MTJ is smaller than about 75% of the width of the MTJ. 
   
   
     14. The magnetic random access memory device of  claim 9  wherein at least one of the first and second write line is connected to the MTJ through a buffer layer with a flat contact surface. 
   
   
     15. The magnetic random access memory device of  claim 14  wherein the contact surface between the buffer layer and the MTJ is formed by using a chemical-mechanical polish process to ensure its flatness. 
   
   
     16. The magnetic random access memory device of  claim 5 , wherein the shielding layer further includes ferromagnetic materials. 
   
   
     17. The magnetic random access memory device of  claim 5 , wherein the shielding layer further includes antiferromagnetic materials.